The Wac Corporal was the United States' first sounding rocket, and predates Wernher von Braun's involvement in the development of United States rocket and missile technology.

When reports of German rockets began circulating during World War II, they found a receptive audience in Caltech's GALCIT group (Guggenhiem Aeronautical Laboratory at the California Institute of Technology). This group was the predecessor of NASA's Jet Propulsion Laboratory, but at the time was a small group of rocket enthusiasts under the wing of Theodore von Karman. With funding from the US army's ordinance division they began work on developing missiles.

Frank Malina, one the founder members of GALCIT, headed up the project and proposed developing a sounding rocket as prototype for a military missile. Thus the Wac Corporal was born.

The Wac Corporal's first flight was on October 11, 1945. First, a solid fuel booster, adapted from a Navy air to surface missile, fired, its acceleration activating the Wac Corporal's liquid fuel rocket. After 0.6 seconds, the booster fell away and the Wac Corporal rose to an altitude of over 43 miles.

March 31st, 1947 was the last flight of the Wac Corporal program, with 17 launches under its belt. One flight reached an altitude of over 50 miles on May 22, 1946, thus becoming the first American rocket to enter space, albeit briefly.

It was replaced by the Aerobee rocket, built by a commercial company, Aerojet, founded by members of GALCIT. However, it was used as the second stage on a later sounding rocket, Project Bumper, which combined the Wac Corporal with a captured V-2 rocket.

The Wac Corporal was10 inches in diameter and stood 24 feet high with its solid fuel booster.